Resin structure

ABSTRACT

A resin structure includes a first resin body having an annular first side wall portion, a second resin body having a second side wall portion, and a third resin body having a bottom wall portion and an annular third side wall portion connected to the bottom wall portion. The second resin body is assembled to the first resin body, such that an upper edge of the second side wall portion and at least a portion of an annular lower edge of the first side wall portion in a circumferential direction are aligned. The third resin body is assembled to the second resin body, such that an annular upper edge of the third side wall portion and at least a lower edge of the second side wall portion are aligned.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No.2019-044087 filed on Mar. 11, 2019, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a resin structure.

Description of Related Art

A resin structure including a plurality of resin bodies assembled toeach other such as a relay box (an electric connection box) mounted on avehicle is widely known in the related art.

-   [Patent Literature 1] JP-A-2017-022824

In the resin structure described above, a gap may occur in alignmentportions between the resin bodies assembled to each other due torelative movement (backlash) between the resin bodies. Accordingly, in acase of high pressure cleaning of blowing water to such a resinstructure from outside (hereinafter, simply referred to as “highpressure cleaning”), water is likely to enter the resin structurethrough the gap. When water entering the resin structure has a largeflow velocity, the water may splash on inner surfaces of a bottom walland a side wall of the resin structure and contact an electroniccomponent such as a relay provided on an upper side in the resinstructure. It is desirable to prevent such splashing of water.

SUMMARY

One or more embodiments provide a resin structure capable of preventingsplashing of water entering the resin structure via a gap between resinbodies assembled to each other.

In an aspect (1), one or more embodiments provide a resin structureincluding a first resin body having an annular first side wall portion,a second resin body having a second side wall portion, and a third resinbody having a bottom wall portion and an annular third side wall portionconnected to the bottom wall portion. The second resin body is assembledto the first resin body, such that an upper edge of the second side wallportion and at least a portion of an annular lower edge of the firstside wall portion in a circumferential direction are aligned. The thirdresin body is assembled to the second resin body, such that an annularupper edge of the third side wall portion and at least a lower edge ofthe second side wall portion are aligned. The third resin body includesa prevention mechanism that prevents flow of water entering an internalspace defined by the bottom wall portion and the third side wall portionvia a gap between the annular lower edge of the first side wall portionand the upper edge of the second side wall portion or a gap between thelower edge of the second side wall portion and the annular upper edge ofthe third side wall portion.

In an aspect (2), the prevention mechanism may be a rib protrudingupward from an inner surface of the bottom wall portion in the internalspace.

In an aspect (3), the second resin body may include a plate-shapedprotrusion protruding from an inner surface of the second side wallportion toward inside of the resin structure and located above the rib.

In an aspect (4), the second resin body may be assembled to the firstresin body such that the upper edge of the second side wall portion anda portion of the annular lower edge of the first side wall portion inthe circumferential direction are aligned. The third resin body may beassembled to the first resin body and the second resin body such thatthe annular upper edge of the third side wall portion and an annularlower edge including a part other than the portion of the annular loweredge of the first side wall portion in the circumferential direction andthe lower edge of the second side wall portion are aligned.

According to the aspect (1), a resin structure has a structure in whichthe second side wall portion is interposed between the first side wallportion and the third side wall portion. Accordingly, relative movement(backlash) is likely to occur between the first side wall portion andthe second side wall portion and between the second side wall portionand the third side wall portion. Therefore, gaps due to the relativemovement (backlash) are likely to occur in the alignment portion betweenthe first side wall portion and the second side wall portion or thealignment portion between the second side wall portion and the thirdside wall portion. When high pressure cleaning is performed to the resinstructure, water is likely to enter the internal space defined by thebottom wall portion and the third side wall portion of the third resinbody via such gaps. When water entering the inner space has a large flowvelocity, the water may splash on inner surfaces of the bottom wallportion and the third side wall portion and contact components or thelike provided on an upper side in the resin structure.

According to the aspect (1), the prevention mechanism is provided in thethird resin body in order to cope with this problem. Accordingly, theflow of water entering the internal space can be prevented by theprevention mechanism. Therefore, the entering water can be preventedfrom splashing on the inner surfaces of the bottom wall portion and thethird side wall portion and the waterproof property for the componentsprovided on the upper side in the resin structure can be enhanced.

In the aspect (1), another aspect in addition to the aspect (4) may alsobe included, in which the second resin body is assembled to the firstresin body such that the annular upper edge of the annular second sidewall portion and the annular lower edge of the first side wall portionare aligned, and the third resin body is assembled to the second resinbody such that the annular upper edge of the third side wall portion andthe annular lower edge of the annular second side wail portion arealigned.

According to the aspect (2), water entering the inner surface of thebottom wall portion in the internal space collides with the rib so thatthe water flow can be prevented. As a result, the flow of water enteringthe inner surface of the bottom wall in the internal space can beeffectively prevented with a simple configuration.

According to the aspect (3), splashing water above the rib due to thecollision with the rib collides with the protrusion of the second resinbody so that the water can be prevented from moving upward further fromthe protrusion. As a result, the waterproof property for the componentsor the like located above the protrusion of the second resin body can beenhanced.

According to the aspect (4), the second side wall portion is interposedbetween the first side wall portion and the third side wall portion onlyin a portion of the resin structure in the circumferential direction andthe first side wall portion and the third side wall portion are directlyassembled in a portion other than the portion of the resin structure inthe circumferential direction. Therefore, water may enter the internalspace from outside only in this portion in the circumferential directionvia a gap in the alignment portion between the first side wall portionand the second side wall portion or the alignment portion between thesecond side wall portion and the third side wall portion. Also in thisstructure, according to the present invention, the flow of waterentering the internal space via the gap can be prevented by theprevention mechanism and the entering water can be prevented fromsplashing to the inner surface of the third side wall portion from theinner surface of the bottom wall portion.

According to one or more embodiments, it is possible to provide a resinstructure capable of preventing splashing of water entering the resinstructure via a gap between resin bodies assembled to each other.

The present invention is briefly described above. Details of the presentinvention will be clarified by reading a mode for carrying out thepresent invention described below with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a resin structure according to anembodiment.

FIG. 2 is a perspective view of the resin structure in which only afirst upper cover and a second upper cover are disassembled.

FIG. 3 is an enlarged perspective view of a front end portion of aframe.

FIG. 4 is a perspective view of an under cover.

FIG. 5 is a plan view of the under cover.

FIG. 6 is a perspective view of a lower cover.

FIG. 7 is an enlarged plan view of a front end portion of the lowercover.

FIG. 8 is a perspective view showing a state in which the frame, theunder cover, and the lower cover are assembled to each other.

FIG. 9 shows a positional relationship between a rib of the lower coverand a protrusion of the under cover.

DETAILED DESCRIPTION Embodiment

Hereinafter, a resin structure 1 according to an embodiment of thepresent invention shown in FIG. 1 will be described with reference tothe drawings. The resin structure 1 is typically a relay box (anelectric connection box) that is mounted on a vehicle and accommodateselectronic components such as a relay. Hereinafter, “from-reardirection”, “width direction”, “up-lower direction”, “front”, “rear”,“upper”, and “lower” are defined as is shown in FIG. 1 for convenienceof description. The “front-rear direction”, the “width direction”, andthe “upper-lower direction” are orthogonal to one another. When theresin structure 1 is mounted on the vehicle, the “font-rear direction”,the “width direction”, and the “upper-lower direction” correspond to thefront-rear direction, the width direction, and the upper-lower directionof the vehicle, respectively.

As shown in FIGS. 1 and 2, the resin structure 1 includes a frame 2, afirst front cover 3 and a second front cover 4 assembled above a frontend portion of the frame 2, a first upper cover 5 assembled above theframe 2 to block an upper opening of a rear region of the frame 2, asecond upper cover 6 assembled above the frame 2 and the first frontcover 3 to block an upper opening of a front region of the frame 2 andthe first front cover 3, an under cover 7 assembled below the front endportion of the frame 2, a lower cover 8 assembled below the frame 2 andunder cover 7 to block lower openings of the frame 2 and the under cover7, and a side cover 9 assembled to an outer surface (a side surface) ofthe frame 2 on its one side in the width direction. All the eightcomponents constituting the resin structure 1 are resin molded bodies.

As shown in FIG. 2, electronic components (and other components) R suchas a relay are accommodated inside the frame 2 and the first front cover3 (and the second front cover 4). The present invention relates tostructures of the frame 2, the under cover 7, and the lower cover 8 ofthe resin structure 1. Accordingly, only the structures of the frame 2,the under cover 7, and the lower cover 8 will be described in detailbelow.

The frame 2 will be described first. As shown in FIGS. 1 to 3, the frame2 includes an annular side wall portion 11 constituting most of theappearance of a side surface of the resin structure 1. The side wallportion 11 is integrally provided with a locking portion 12 on outersurfaces of a plurality of positions (three positions in the presentembodiment) on a front end portion of a lower end portion of the sidewall portion 11. The locking portion 12 has a through hole extending inthe upper-lower direction. The locking portion 12 has a function ofassembling the under cover 7 to the frame 2.

The side wall portion 11 is integrally provided with a locking portion13 on outer surfaces of a plurality of positions (eight positions in thepresent embodiment) on the lower end portion of the side wall portion 11in the circumferential direction. The locking portion 13 has a throughhole extending in the upper-lower direction. The locking portion 13 hasa function of assembling the lower cover 8 to the frame 2.

As shown in FIG. 3, the side wall portion 11 is provided with arectangular concave portion 14 on an outer surface of one position onthe lower end portion of the side wall portion 11. The concave portion14 is recessed and opened in the thickness direction of the side wailportion 11. The concave portion 14 has a function of fitting and lockinga distal end portion of an extension piece 35 of the lower cover 8described below.

Next, the under cover 7 will be described. As shown in FIGS. 4 and 5,the under cover 7 includes a side wall portion 21. An upper edge of theside wall portion 21 has a shape corresponding to a front end portion (aportion in the circumferential direction) of an annular lower edge ofthe side wall portion 11 of the frame 2. The side wall portion 21 isintegrally provided with a flat plate-shaped protrusion 22 protruding inthe horizontal direction from an inner surface of the side wall portion21 toward the inside of the resin structure 1.

The side wall portion 21 is integrally provided with a locking piece 23extending upward on outer surfaces of a plurality of positions (threepositions in the present embodiment) on an upper end portion of the sidewall portion 21 in the circumferential direction. The locking piece 23has a function of assembling the under cover 7 to the frame 2.

The side wall portion 21 is integrally provided with a locking portion24 on an outer surface of one position on a lower end portion of theside wall portion 21. The locking portion 24 has a through holeextending in the upper-lower direction. The locking portion 24 has afunction of assembling the lower cover 8 to the under cover 7.

The side wall portion 21 is integrally provided with a holding portion25 on an outer surface of another position on the lower end portion ofthe side wall portion 21. The holding portion 25 has a through hole 26extending in the upper-lower direction. The holding portion 25 has afunction of holding the extension piece 35 of the lower cover 8. Theholding portion 25 is provided with a locking claw 27 that locks alocking step portion 36 provided on the extension piece 35 of the lowercover 8 described below.

The under cover 7 has a semi-cylindrical groove 28 opened downward at alower end portion thereof. The groove 28 has a function of constitutingan upper part of an inner wall defining an insertion hole H (see FIGS. 1and 8) through which electric wires (not shown) led out from the insideof the resin structure 1 are inserted.

Next, the lower cover 8 will be described. As shown in FIGS. 6 and 7,the lower cover 8 integrally includes an annular side wall portion 31constituting most of the appearance of a lower side surface of the resinstructure 1, and a bottom wall portion 32 constituting most of theappearance of a bottom surface of the resin structure 1. The bottom wallportion 32 blocks an annular lower opening of the side wall portion 31.

An annular upper edge of the side wail portion 31 has a shapecorresponding to an annular lower edge constituted by (i) a part otherthan the front end portion (the portion in the circumferentialdirection), to which the under cover 7 is assembled, of the annularlower edge of the side wall portion 11 of the frame 2 and (ii) a loweredge of the under cover 7.

The bottom wall portion 32 has a shape inclined upward from front torear. Accordingly, an inner surface of the bottom wall portion 32 alsohas a shape inclined upward from front to rear.

The side wall portion 31 is integrally provided with a locking piece 33extending upward on outer surfaces of a plurality of positions (eightpositions in the present embodiment) on an upper end portion of the sidewall portion 31 in the circumferential direction. The locking piece 33has a function of assembling the lower cover 8 to the frame 2.

The side wall portion 31 is integrally provided with a locking piece 34extending upward on an outer surface of one position on a front endportion of the upper end portion of the side wall portion 31. Thelocking piece 34 has a function of assembling the lower cover 1 to theunder cover 7.

The side wall portion 31 is integrally provided with the extension piece35 extending upward on an outer surface of another position on the frontend portion of the upper end portion of the side wall portion 31. Aswill be described below, the extension piece 35 has a function ofholding the under cover 7 in cooperation with the concave portion 14 ofthe frame 2. The extension piece 35 includes the locking step portion 36on an outer surface thereof. The extension height of the extension piece35 is larger than the protruding height of the locking pieces 33, 34.

The lower cover 8 has a semi-cylindrical groove 37 opened upward at anupper end portion of a front end portion thereof. The groove 37 has afunction of constituting a lower part of the inner wall defining theinsertion hole (see FIGS. 1 and 8) through which electric wires (notshown) led out from the inside of the resin structure 1 are inserted.

The bottom wall portion 32 is provided with a plurality of ribs 38 in aninternal space defined by the side wall portion 31 and the bottom wallportion 32 at a front end portion of the bottom wall portion 32. Theplurality of ribs 38 protrude upward from the inner surface of thebottom wall portion 32. In particular, in the present embodiment as isshown in FIG. 7, a plurality of ribs 38 extending in the width directionfrom the side wall portion 31 on one side in the width direction to theother side in the width direction are arranged side by side in thefront-rear direction. A plurality of ribs 38 extending in the widthdirection from the side wall portion 31 on the other side in the widthdirection to the one side in the width direction are also arranged sideby side in the front-rear direction. The function of the ribs 38 will bedescribed below.

The bottom wall portion 32 has a water drain hole 39 in a position ofthe front end portion of the bottom wall portion 32 that does notinterfere with the ribs 38. The water drain hole 39 penetrates in theupper-lower direction. The structures of the frame 2, the under cover 7,and the lower cover 8 are described above.

Next, procedures for assembling the frame 2, the under cover 7, and thelower cover 8 will be described. When assembling the frame 2, the undercover 7, and the lower cover 8, the under cover 7 is first assembled tothe frame 2. To assemble the under cover 7 to the frame 2, a pluralityof locking pieces 23 (see FIG. 4) of the under cover 7 are inserted andlocked to through holes of a plurality of locking portions 12 of theframe 2 from below. Accordingly, as shown in FIG. 8, the under cover 7is assembled to the frame 2 such that the upper edge of the side wallportion 21 of the under cover 7 and the front end portion (the portionin the circumferential direction) of the annular lower edge of theannular side wall portion 11 of the frame 2 are aligned.

Next, the lower cover 8 is assembled to the frame 2 and the under cover7. To assemble the lower cover 8 to the frame 2 and the under cover 7,the extension piece 35 (see FIG. 6) of the lower cover 8 is firstinserted into the through hole 26 (see FIG. 4) of the holding portion 25of the under cover 7 from below. Next, with the state in which theextension piece 35 is inserted into the through hole 26 (that is, theextension piece 35 is held by the holding portion 25) maintained, onelocking piece 34 of the lower cover 8 is inserted and locked to athrough bole of one locking portion 24 of the under cover 7, a pluralityof locking pieces 33 of the lower cover 8 are respectively inserted andlocked to through holes of a plurality of locking portions 13 of theframe 2, and the locking step portion 36 of the extension piece 35 islocked to the locking claw 27 of the holding portion 25. In this way,the lower cover 8 can be assembled to the frame 2 and the under cover 7with the state in which the extension piece 35 is held by the holdingportion 25 maintained. Accordingly, this operation can be easilyperformed.

Accordingly, as shown in FIG. 8, the lower cover 8 is assembled to theframe 2 and the under cover 7 such that the annular upper edge of theannular side wall portion 31 of the lower cover 8 and the annular loweredge constituted by (i) the part other than the front end portion (theportion in the circumferential direction), to which the under cover 7 isassembled, of the annular lower edge of the side wall portion 11 of theframe 2 and (ii) the lower edge of the side wall portion 21 of the undercover 7 are aligned. Accordingly, the assembly of the frame 2, the undercover 7, and the lower cover 8 is completed.

When the assembly of the frame 2, the under cover 7, and the lower cover8 is completed (an assembly completed state), as shown in FIG. 8, theinsertion hole It into which electric wires (not shown) are inserted isdefined by the groove 28 of the under cover 7 and the groove 37 of thelower cover 8.

In the assembly completed state, as shown in FIG. 9, the protrusion 22of the under cover 7 is located above a plurality of ribs 38 of thelower cover 8. A function of the arrangement relationship between theribs 38 and the protrusion 22 will be described below.

The resin structure 1 has a structure in which the under cover 7 isinterposed between the frame 2 and the lower cover 8. Accordingly,relative movement (backlash) is likely to occur between the frame 2 andthe under cover 7 and between the under cover 7 and the lower cover 8.Therefore, gaps due to the relative movement (backlash) may occur in analignment portion C1 (see FIG. 8) between the side wall portion 11 andthe side wall portion 21 or an alignment portion C2 (see FIG. 8) betweenthe side wall portion 21 and the side wall portion 31. When highpressure cleaning is performed to the resin structure 1 from a frontside, water is likely to enter the internal space defined by the bottomwall portion 32 and the side wall portion 31 of the lower cover 8 viasuch gaps. When water entering the inner space has a large flowvelocity, the water may splash on inner surfaces of the bottom wallportion 32 and the side wall portion 31 (see white arrows in FIGS. 6 and7) and contact the electronic components R (see FIG. 2) provided on anupper side in the resin structure 1.

For this reason, the resin structure 1 is provided with the plurality ofribs 38 on an inner surface of the lower cover 8. Accordingly, waterentering the inner surface of the bottom wall portion 32 in the internalspace from the front side collides with the plurality of ribs 38 so thatthe water flow can be prevented. Therefore, the entering water can beprevented from splashing on the inner surfaces of the bottom wallportion 32 and the side wall portion 31 and the waterproof property forthe electronic components R provided on the upper side in the resinstructure 1 can be enhanced.

In addition, splashing water above the ribs 38 due to the collision withthe ribs 38 collides with the protrusion 22 of the under cover 7 locatedabove the ribs 38 so that the water can be prevented from moving upwardfurther from the protrusion 22. As a result, the waterproof property forthe electronic components R located above the protrusion 22 of the undercover 7 can be enhanced. The function of the arrangement relationshipbetween the ribs 38 and the protrusion 22 is described above.

In the assembly completed state, the distal end portion of the extensionpiece 35 of the lower cover 8 held by the holding portion 25 of theunder cover 7 is locked to the concave portion 14 of the frame 2 bybeing fitted into the concave portion 14. In other words, the undercover 7 is held (fixed) at an intermediate portion of the extensionpiece 35 whose base end portion and distal end portion are fixed by theframe 2 and the lower cover 8, respectively. Therefore, relativemovement (backlash) is less likely to occur between the frame 2 and theunder cover 7 and between the under cover 7 and the lower cover 8, andgaps due to the relative movement (backlash) is less likely to occur inthe alignment portion C1 between the side wall portion 11 of the frame 2and the side wall portion 21 of the under cover 7 and the alignmentportion C2 between the side wall portion 21 of the under cover 7 and theside wall portion 31 of the lower cover 8. This makes it less likely forwater to enter the resin structure 1 through these gaps.

<Functions and Effects>

According to the resin structure 1 in the embodiment of the presentinvention, relative movement (backlash) is likely to occur between theframe 2 and the under cover 7 and between the under cover 7 and thelower cover 8 due to the structure in which the under cover 7 isinterposed between the frame 2 and the lower cover 8. Therefore, gapsdue to the relative movement (backlash) may occur in the alignmentportion C1 between the side wall portion 11 and the side wall portion 21or the alignment portion C2 between the side wall portion 21 and theside wall portion 31. When high pressure cleaning is performed to theresin structure 1 from the front side, water is likely to enter theinternal space defined by the bottom wall portion 32 and the side wallportion 31 of the lower cover 8 via such gaps. When water entering theinner space has a large flow velocity, the water may splash on the innersurfaces of the bottom wall portion 32 and the side wall portion 31 (seewhite arrows in FIGS. 6 and 7) and contact the electronic components Rprovided on the upper side in the resin structure 1.

For this reason, the resin structure 1 is provided with the plurality ofribs 38 on the inner surface of the lower cover 8. Accordingly, waterentering the inner surface of the bottom wall portion 32 in the internalspace from the front side collides with the plurality of ribs 38 so thatthe water flow can be prevented. Therefore, the entering water can beprevented from splashing on the inner surfaces of the bottom wallportion 32 and the side wall portion 31 and the waterproof property forthe electronic components R provided on the upper side in the resinstructure 1 can be enhanced.

In addition, splashing water above the ribs 38 due to the collision withthe ribs 38 collides with the protrusion 22 of the under cover 7 locatedabove the ribs 38 so that the water can be prevented from moving upwardfurther from the protrusion 22. As a result, the waterproof property forthe electronic components R located above the protrusion 22 of the undercover 7 can be enhanced.

Other Embodiments

The present invention is not limited to the above embodiment and variousmodifications can be adopted within the scope of the present invention.For example, the present invention may be appropriately modified,improved or the like. In addition, materials, shapes, dimensions,numbers, arrangement locations and the like of elements in the aboveembodiment are optional and not limited as long as the object of thepresent invention can be achieved.

In the above embodiment, the under cover 7 is interposed between theframe 2 and the lower cover 8 only in a portion of the resin structure 1in the circumferential direction and the frame 2 and the lower cover 8are directly assembled in a portion other than the portion of the resinstructure 1 in the circumferential direction. In contrast, the undercover 7 may be interposed between the frame 2 and the lower cover 8 overthe entire circumference of the resin structure 1 in the circumferentialdirection. In this case, the under cover 7 is assembled to the frame 2such that the annular upper edge of the side wall portion 21 of theannular under cover 7 and the annular lower edge of the side wallportion 11 of the frame 2 are aliened, and the lower cover 8 isassembled to the under cover 7 such that the annular upper edge of theside wall portion 31 of the lower cover 8 and the annular lower edge ofthe annular side wall portion 21 are aliened.

The above embodiment adopts a plurality of ribs 38 as a “preventionmechanism” of the present invention. In contrast, one rib 38 may beemployed as the “prevention mechanism” of the present invention. Inaddition, the “prevention mechanism” of the present invention may adoptany mechanism other than the “rib” as long as the mechanism has afunction of preventing the flow of water entering the internal spacedefined by the bottom wall portion 32 and the side wall portion 31 ofthe lower cover 8.

The above embodiment adopts the flat plate-shaped protrusion 22protruding in the horizontal direction from the inner surface of theside wall portion 21 of the under cover 7 toward the inside of the resinstructure 1 as a “protrusion” of the present invention. In contrast, the“protrusion” of the present invention may have any shape and posture aslong as the protrusion is located above the rib 38 and protrudes fromthe inner surface of the side wall portion 21 toward the inside of theresin structure 1.

In the above embodiment, the resin structure 1 is a relay box (anelectric junction box) that accommodates a plurality of electroniccomponents R, but the resin structure 1 may have functions other thanthe relay box (the electric junction box).

Here, features of the above embodiment of the resin structure 1according to the present invention are briefly summarized and listed inthe following [1] to [4].

-   [1] A resin structure (1) comprising:

a first resin body (2) having an annular first side wall portion (11);

a second resin body (7) having a second side wall portion (21); and

a third resin body (8) having a bottom wall portion (32) and an annularthird side wall portion (31) connected to the bottom wall portion (32),

wherein the second resin body (7) is assembled to the first resin body(2), such that an upper edge of the second side wall portion (21) and atleast a portion of an annular lower edge of the first side wall portion(11) in a circumferential direction are aligned,

wherein the third resin body (8) is assembled to the second resin body(7), such that an annular upper edge of the third side wall portion (31)and at least a lower edge of the second side wall portion (21) arealigned, and

wherein the third resin body (8) includes a prevention mechanism (38)that prevents flow of water entering an internal space defined by thebottom wall portion (32) and the third side wall portion (31) via a gapbetween the annular lower edge of the first side wall portion (11) andthe upper edge of the second side wall portion (21) or a gap between thelower edge of the second side wall portion (21) and the annular upperedge of the third side wall portion (31).

-   [2] The resin structure (1) according to [1],

wherein the prevention mechanism is a rib (38) protruding upward from aninner surface of the bottom wall portion (32) in the internal space.

-   [3] The resin structure (1) according to [2],

wherein the second resin body (7) includes a plate-shaped protrusion(22) protruding from an inner surface of the second side wall portion(21) toward inside of the resin structure (1) and located above the rib(38).

[4] The resin structure (1) according to any one of [1] to [3],

wherein the second resin body (7) is assembled to the first resin body(2) such that the upper edge of the second side wall portion (21) and aportion of the annular lower edge of the first side wall portion (11) inthe circumferential direction are aligned, and

wherein the third resin body (8) is assembled to the first resin body(2) and the second resin body (7) such that the annular upper edge ofthe third side wall portion (31) and an annular lower edge including apart other than the portion of the annular lower edge of the first sidewall portion (11) in the circumferential direction and the lower edge ofthe second side wall portion (21) are aligned.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1 resin structure

2 frame (first resin body)

7 under cover (second resin body)

8 lower cover (third resin body)

11 side wail portion (first side wall portion)

21 side wall portion (second side wall portion)

22 protrusion

31 side wall portion (third side wall portion)

32 bottom wall portion

38 rib (prevention mechanism)

C1 alignment portion

C2 alignment portion

What is claimed is:
 1. A resin structure comprising: a first resin bodyhaving an annular first side portion; a second resin body having asecond side wall portion; and a third resin both having a bottom wallportion and an annular third side wall portion connected to the bottomwall portion, wherein the second resin body is assembled to the firstresin body, such that ail upper edge of the second side wall portion andat least a portion of an annular lower edge of the first side wallportion in a circumferential direction are aligned, wherein the thirdresin body is assembled to the second resin body, such that an annularupper edge of the third side wall portion and at least a lower edge ofthe second side wall portion are aligned, and wherein the third resinbody includes a prevention mechanism that prevents flow of waterentering an internal space defined by the bottom wall portion and thethird side wall portion via a gap between the annular lower edge of thefirst side wall portion and the upper edge of the second side wallportion or a gap between the lower edge of the second side wall portionand the annular upper edge of the third side wail portion.
 2. The resinstructure according to claim 1, wherein the prevention mechanism is arib protruding upward from an inner surface of the bottom wall portionin the internal space.
 3. The resin structure according to claim 2,wherein the second resin body includes a plate-shaped protrusionprotruding from an inner surface of the second side wall portion towardinside of the resin structure and located above the rib.
 4. The resinstructure according to claim 1, wherein the second resin body isassembled to the first resin both such that the upper edge of the secondside wall portion and a portion of the annular lower edge of the firstside wall portion in the circumferential direction are aligned, andwherein the third resin body is assembled to the first resin body andthe second resin body such that the annular upper edge of the third sidewall portion and an annular lower edge including a part other than theportion of the annular lower edge of the first side wall portion in thecircumferential direction and the lower edge of the second side wallportion are aligned.